We're getting two kittens soon. The lady we are getting them from said they're on whiskas at the moment (they were originally meant to be going to another family who asked that she use that brand as it's what they can get easily in their local shop) but she said she personally prefers iams and would never use whiskas with her own cats.
We're happy to stick with whiskas, but if that's not great nutritionally I'm happy to change to something better quality.
I know that if we do change over we need to do it very gradually.